Metallized paper-based packaging layer material, comprising at least two barrier layers made of a vinyl alcohol polymer

Abstract

A packaging layer material having a base layer made of paper, a first barrier coating assembly made of a vinyl alcohol polymer, and a second barrier coating assembly made of metal or a metal compound which is deposited onto a support surface in a vapor deposition process, the first barrier coating assembly has more than one layer made of the vinyl alcohol polymer, wherein the layers of the first barrier coating assembly are arranged directly one after the other.

Description

[0001] This Application claims priority in PCT application PCT / EP2024 / 053186 filed Feb. 8, 2024, which claims priority in German Patent Application DE 10 2023 103 298.4 filed on Feb. 10, 2023, which are incorporated by reference herein.

[0002] The present invention relates to a packaging layer material comprising a base layer of paper, a first barrier coating assembly of a vinyl alcohol polymer and a second barrier coating assembly of a metal or a metal compound which is deposited on a carrier surface in a vapor deposition process.BACKGROUND OF THE INVENTION

[0003] Such a packaging layer material, whether in roll material or sheet material form, is used for the production of packaging. The packaging may be packaging with packaging spaces closed by seals or adhesives, such as pouch packaging, for example three-or four-side sealed pouches or stand-up pouches, or may be packaging formed by wrapping the goods to be packaged.

[0004] Such packaging layer materials are expected to provide a barrier against a variety of external influences on the packaged product. At the same time, they should be environmentally compatible and recyclable. Barriers against oxygen migration are particularly important in order to prevent or at least delay oxidation of the packaged goods, as are barriers against water vapor or moisture in order to prevent unwanted softening or even rotting of the packaged product.

[0005] In the case of paper-based packaging layer materials, a barrier protection of the paper layer against migration of moisture, oil, and / or fat from the packaged product into the paper layer may also be necessary. Paper is often absorbent due to its porosity and can permanently store moisture, oil, and / or grease in its structure, which, however, usually adversely affects the structure in terms of its strength and / or appearance.

[0006] Recyclability and environmental compatibility are provided by the base layer made of paper. However, in the prior art, barriers are often achieved by metal foils, the production of which, however, requires a high amount of energy and resources. Alternatively, barriers can be achieved by polymer coatings made of polyvinylidene chloride, which, however, considerably impairs the recyclability of the layer composite produced in this way.SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a paper-based packaging layer material with a high barrier effect that is as environmentally compatible and recyclable as possible.

[0008] The present invention solves this problem with a packaging layer material mentioned at the beginning, whose first barrier coating assembly has more than one layer of the vinyl alcohol polymer, wherein the layers of the first barrier coating assembly are arranged directly one after the other.

[0009] The use of paper as the material for the base layer ensures that the structure-forming portion of the packaging layer material is recyclable. By forming the first barrier coating assembly from a vinyl alcohol polymer, the first barrier coating assembly can be formed as a water-soluble separating layer which, upon contact with water, dissolves and thereby separates the paper base layer from further layers of the packaging layer material.

[0010] By stacking at least two layers of the vinyl alcohol polymer, one layer of the first barrier coating assembly can cover any defects in another layer of the first barrier coating assembly. In this way, any cracks, tears, and holes that occur in one layer can be covered by material from another layer, and any impairment of the barrier against oxygen migration provided by the first barrier coating assembly can be reduced or even completely eliminated.

[0011] The paper layer preferably has a weight per unit area in the range of 30 to 100 g / m2, particularly preferably in the range of 45 to 90 g / m2. While the paper base layer can in principle be formed from two or more interconnected partial paper layers, the paper base layer is preferably formed from a single paper layer.

[0012] The first barrier coating assembly preferably has a weight per unit area in the range of 1 to 10 g / m2.

[0013] While a vinyl alcohol polymer is susceptible to attack by water, but provides a very good barrier against oxygen migration, the second barrier coating assembly, which is formed with a very low thickness in the range of 10 to 80 nm as a coating deposited from a vapor phase, forms an excellent barrier against migration of water vapor or moisture through the packaging layer material. Depending on the thickness and material of the deposited coating of metal or a metal compound, the second barrier coating assembly can also form a light barrier and thus protect light-sensitive packaged products.

[0014] In principle, the first barrier coating assembly can have a plurality of layers of vinyl alcohol polymer, for example two or three or four layers. However, tests have shown that even a stacked arrangement of exactly two layers of vinyl alcohol polymer provides an excellent and, above all, uninterrupted barrier against oxygen migration through the packaging layer material over its entire surface area. In order to avoid unnecessary effort that does not contribute to any significant improvement in the oxygen barrier effect, the first barrier coating assembly preferably comprises exactly two layers of vinyl alcohol polymer.

[0015] Each layer of the first barrier coating assembly preferably has a weight per unit area in the range of 0.5 to 5g / m2. This does not mean that all layers of the first barrier coating assembly have a uniform weight per unit area, although this is preferred for manufacturing reasons.

[0016] Preferably, the packaging layer material has an oxygen permeability over its total thickness of not more than 1.0, preferably not more than 0.85 cm3 / (m2·d·bar), determined in accordance with DIN 53380-3 at 23° C. and 85% relative humidity, and a water vapor permeability of not more than 1.0, preferably not more than 0.85 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0017] Although the individual layers of the first barrier coating assembly may contain different vinyl alcohol polymers, the use of vinyl alcohol polymers based on at least the same monomer or the same monomers is preferred. It is particularly preferred that all layers of the first barrier coating assembly are formed from the same vinyl alcohol polymer. This ensures particularly good adhesion of the individual layers of the first barrier coating assembly to one another.

[0018] The vinyl alcohol polymer is preferably a modified vinyl alcohol polymer whose properties in terms of moisture resistance and elasticity are optimized by the processing method using temperature and humidity control during drying, which is particularly good at compensating for defects in one layer, known in the technical field as “pinholes,” by means of an overlying layer.

[0019] The vinyl alcohol polymer layers are preferably applied by printing, for example by roller coating. This allows vinyl alcohol polymer layers applied one after the other by printing to be subject to different influences. Consequently, each of the layers can and will usually form cracks, tears and, in particular, the above-mentioned pinholes at different locations, so that, as already explained above, defects in one layer are covered by the other layer and vice versa.

[0020] It is particularly preferred that the first barrier coating assembly is applied directly to a surface of the paper base layer.

[0021] According to a preferred refinement of the present invention, the vinyl alcohol polymer may comprise or be polyvinyl alcohol (PVOH) and / or butenediol-vinyl alcohol copolymer (BVOH). Polyvinyl alcohol, particularly in the modified form mentioned above, can provide particularly good defect compensation for layers arranged one above the other. In addition to the barrier against oxygen migration, polyvinyl alcohol also provides a very good barrier against the migration of mineral oil through the packaging layer material.

[0022] Butenediol-vinyl alcohol copolymer has the advantage of excellent biodegradability.

[0023] In principle, it is conceivable to deposit the second barrier coating assembly directly onto a surface of the paper base layer. However, this usually requires pretreatment of the carrier surface formed by the paper base layer in order to close pores in the typically porous paper. Otherwise, due to the low thickness of the deposited second barrier coating assembly, fibers of the paper base layer could be coated with the metal or metal compound, but without closing the or all pores in the material, so that the barrier effect desired by the second barrier coating assembly could be lost. To avoid the expense of pretreating the paper, the first barrier coating assembly is preferably arranged between the paper base layer and the second barrier coating assembly. In particular, one surface of the first barrier coating assembly forms the carrier surface of the second barrier coating assembly. If necessary, a primer layer may be provided between the first and second barrier coating assemblies. However, it is preferable to deposit the second barrier coating assembly directly onto the first barrier coating assembly.

[0024] A further advantage of arranging the first barrier coating assembly between the paper base layer and the second barrier coating assembly lies in the protection of the first barrier coating assembly against moisture attack by the second barrier coating assembly, which shields the first barrier coating assembly.

[0025] The second barrier coating assembly comprises a deposited layer of metal or of a metal oxide as the metal compound mentioned above. The metal can be any metal, such as gold, silver, platinum, copper, or aluminum. A deposited metal layer is preferably an aluminum layer or a layer of an aluminum alloy. Such a metal layer can be provided to be light-tight.

[0026] If a metal oxide is desired as the deposited second barrier coating assembly, which can often be deposited in an even thinner layer than metal, the material of the second barrier coating assembly comprises or is silicon oxide or aluminum oxide.

[0027] In a preferred refinement of the present invention, a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer in order to protect the deposited, i.e. usually vapor-deposited, second barrier coating assembly. It has been found that when the second barrier coating assembly deposited from the vapor phase is arranged between two flexible layers, in particular polymer layers, it is particularly mechanically resistant and can be bent or even folded without any risk of cracks or tears in the second barrier coating assembly.

[0028] With a suitable choice of material, the polymer coating can be applied directly to a surface of the second barrier coating assembly. If necessary, a primer layer can be applied to the second barrier coating assembly to increase the adhesion of the polymer coating to the second barrier coating assembly.

[0029] The polymer coating may comprise or be a vinyl alcohol polymer if an even higher barrier effect against oxygen migration through the packaging layer material is desired. When PVOH is used as the vinyl alcohol polymer of the polymer coating, the barrier effect against migration of mineral oil through the packaging layer material can also be increased. Any of the vinyl alcohol polymers mentioned above are particularly suitable as the vinyl alcohol polymer. The vinyl alcohol polymer is particularly preferred as a modified vinyl alcohol polymer, particularly preferred as a modified PVOH, although a formulation of the modified PVOH of the polymer coating that differs from the modified PVOH of the first barrier coating assembly is preferred. Reference is made to the above description for the modification of the PVOH.

[0030] Preferably, the PVOH of the polymer coating has a higher degree of crosslinking than PVOH, preferably than the entire PVOH of the first barrier coating arrangement, in order to improve the adhesion of a further polymer, in particular the biopolymer coating explained below, thereto. Preferably, the PVOH of the first barrier coating assembly has a higher degree of crystallization than the PVOH of the polymer coating in order to improve the moisture stability of the first barrier coating assembly. The adjustment of a relative or absolute degree of crosslinking and / or a relative or absolute degree of crystallization is also a modification of the PVOH within the meaning of the present application.

[0031] Alternatively, the polymer coating may comprise or be a polyolefin. This allows the water vapor barrier provided by the second barrier coating assembly to be further improved in its effect, especially when polyethylene is used as the polyolefin of the polymer coating. The polymer coating made of polyolefins, in particular polyethylene, can thus cover any cracks, gaps or holes present in the second barrier coating assembly and thus close barrier gaps or at least reduce their effect.

[0032] The polymer coating is preferably applied as a water-based dispersion in a print application, for example by roller coating.

[0033] The polymer coating has a preferred weight per unit area in the range of 0.5 to 5 g / m2, wherein an application in the range of 1 to 2.5 g / m2 is preferred and a weight per unit area of 1.5 g / m2 is particularly preferred.

[0034] All weights per unit area mentioned in the present application refer to the respective layer in the dry state.

[0035] A biopolymer coating may also be arranged on the side of the second barrier coating assembly facing away from the paper base layer. For the purposes of this application, a biopolymer is any biodegradable polymer that complies with European standard EN 13432. A biodegradable polymer is generally a polymer that can be decomposed by microorganisms such as fungi or bacteria, by means of enzymes under certain conditions, in less than one year. The decomposition takes place mainly through oxidation and hydrolysis processes to the decomposition products water, carbon dioxide or methane and biomass.

[0036] The above-mentioned polymer coating is preferably arranged between the second barrier coating assembly and the biopolymer coating. Then, if a vinyl alcohol polymer, in particular PVOH, is selected as one or as the material of the polymer coating, the vinyl alcohol polymer can additionally act as a tie layer to increase the adhesion of the biopolymer coating to the layer composite already described above.

[0037] According to a particularly preferred refinement of the present invention, the biopolymer coating may be based on a natural protein or may be constructed from a protein polymer based on natural protein, for example comprising or consisting of casein, or may comprise a biodegradable polyester or be formed from such a polyester. A particularly preferred polyester made from biopolymer is polybutylene succinate adipate, or PBSA for short.

[0038] If a polyolefin is chosen as the polymer coating, a primer is preferably applied, preferably by extrusion, to increase the adhesion of the biopolymer coating to the polymer coating. The primer is particularly preferred to be coextruded with the biopolymer.

[0039] The biopolymer coating preferably has a weight per unit area in the range of 0.5 to 50 g / m2. The weights per unit area used for the different biopolymers are preferably different. A biopolymer based on natural protein preferably has a weight per unit area in the range of 0.5 to 5 g / m2, a particularly preferred weight per unit area being in the range of 2.8 to 4.2 g / m2, and a particularly preferred biopolymer coating made from a protein polymer based on a natural protein having a weight per unit area of 3.5 g / m2. The biopolymer based on natural protein is preferably applied in aqueous dispersion by printing, for example by roller coating, preferably directly onto the polymer coating lying immediately underneath, in particular made of modified PVOH.

[0040] A polyester as the biopolymer of the biopolymer coating, in particular the above-mentioned PBSA, has a preferred weight per unit area of 5 to 50 g / m2, with a more preferred weight per unit area range of 10 to 30 g / m2, and a biopolymer coating made of PBSA in a preferred embodiment has a weight per unit area of 20 g / m2.

[0041] The use of biopolymers, in particular polyester, protects the packaging formed from the packaging layer material against breaking by kinking and also protects the underlying barrier coating assemblies against mechanical damage caused by tearing and puncturing.

[0042] The biopolymer coating, when applied in sufficient thickness, can also be used to anchor closure means, such as so-called “zippers,” in the packaging layer material on the side of the polymer coating.

[0043] If a primer arrangement is necessary to increase the adhesion of the biopolymer coating to the polymer coating, the primer layer provided then has a preferred weight per unit area in the range of 0.5 to 5 g / m2, whereby a weight per unit area in the range of 0.7 to 1.7 g / m2 is particularly preferred. In a preferred embodiment, a primer layer arranged between the polymer coating and the biopolymer coating has a weight per unit area of 0.9 g / m2.

[0044] For easy formation of packaging, the biopolymer coating is preferably sealable or has a sealable exposed surface.

[0045] Biopolymers also provide a further barrier against migration of mineral oil, grease, and moisture through the packaging layer material.

[0046] To provide consumer information, the packaging material preferably has a print application. The print application is preferably applied directly to the paper base layer. Therefore, the print application on the one hand and the first and second barrier coating assemblies, as well as any further polymer layers, preferably all polymer layers, are preferably located on different sides of the paper base layer.

[0047] The colors of the print application are preferably solvent-based colors. However, water-based colors may also be used. Although water in this sense is also an abstract solvent, the term “solvent-based” in the present application refers to the use of solvents other than water.

[0048] To prevent printing inks from rubbing off when touched, the print application may preferably comprise an overprint varnish over a printing ink application. The overprint varnish may be a solvent-based overprint varnish based on nitrocellulose or may be a polyolefin, which is preferably applied as an aqueous dispersion.

[0049] The entire print application, including an overprint varnish, preferably has a weight per unit area of less than 3.2 g / m2 when dry.

[0050] The paper base layer is preferably free of a print-property improving paper coating. This prevents a print-property improving paper coating, which is not present anyway, from breaking and thus inducing the breakage of adjacent coatings. The paper base layer is preferably completely uncoated.

[0051] Preferred embodiments of the packaging layer material presented here only have the layers mentioned above.

[0052] These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section.BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which forms a part hereof and wherein:

[0054] FIG. 1 a roughly schematic cross-sectional view through a first embodiment of a packaging layer material according to the invention, and

[0055] FIG. 2 a roughly schematic cross-sectional view through a second embodiment of a packaging layer material according to the invention.

[0056] The figures are not to scale.DESCRIPTION OF PREFERRED EMBODIMENTS

[0057] Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, FIG. 1 shows a first embodiment of a packaging layer material according to the invention in a roughly schematic cross-sectional view and is generally designated by 10.

[0058] An inner surface 10a of the packaging layer material 10 faces a packaging space V of a package formed from the packaging layer material 10. An opposite outer surface 10b of the packaging layer material 10, on the other hand, faces the external environment U and thus the consumers of the packaging on a packaging formed from the packaging layer material 10.

[0059] The packaging layer material 10 has a paper layer 12 made of uncoated paper with a weight per unit area in the range of 30 to 100 g / m2, preferably 45 to 90 g / m2, as a structure-forming layer. All other layers are supported by the paper layer 12 or applied directly or indirectly to it. The paper of the paper layer 12 is recyclable and is preferably also approved for packaging foodstuffs.

[0060] A first barrier coating assembly 14 is applied, preferably by a printing process, for example in a roller coating process, as an aqueous dispersion to the surface 12a of the paper layer 12 facing the subsequent packaging space V. The barrier coating assembly 14 is applied over the entire surface 12a of the paper layer 12, disregarding edge areas of the packaging layer material 10 which form trimmings in further processing.

[0061] In the present embodiment, the first barrier coating assembly 14 is formed from two layers 16 and 18 of modified polyvinyl alcohol as described above, which are applied one after the other. The layers 16 and 18 each have a weight per unit area in the range of 0.5 to 5 g / m2 and, in the preferred embodiment, each have a weight per unit area of 1.5 g / m2. In the present embodiment, the two layers 16 and 18 of the first barrier coating assembly 14 are identical in terms of material composition and weight per unit area, but this is not necessary.

[0062] The polyvinyl alcohol of the first barrier coating assembly provides a barrier against the migration of oxygen and mineral oil through the packaging layer material 10. Due to the advantageously high degree of crystallinity of the polyvinyl alcohol, the first barrier coating assembly 14 is more stable against moisture attack than conventional polyvinyl alcohol with a lower degree of crystallinity, despite the fundamental moisture sensitivity of polyvinyl alcohol.

[0063] The layers 16 and 18 are preferably applied one after the other so that, when the first layer 16 dries, any defects forming in it, such as cracks, tears, and holes, which could reduce the barrier properties of layer 16, can be covered by material from layer 18 applied immediately onto layer 16. Similarly, cracks, tears, and holes in layer 18 are bridged and covered by the underlying layer 16. It is very unlikely that defects will form in exactly the same place in two successive PVOH-containing barrier layers 16 and 18 of the first barrier coating assembly 14.

[0064] On the free surface 18a of layer 18, which points away from the paper layer 12 and toward the subsequent packaging space V and which is also the free surface 14a of the first barrier coating assembly 14, as a carrier surface an aluminum alloy is deposited as a metallization in a physical or chemical vapor deposition process, preferably in a physical vapor deposition process. The metallization forms a second barrier coating assembly 20, which is 10 to 80 nm thick and, in the present example, provides a barrier against light and against water vapor or moisture.

[0065] The first barrier coating assembly 14 made of modified PVOH forms an advantageously smooth surface 14a, which allows for continuous metallization that is as free of defects as possible.

[0066] A polymer coating 22 is applied to the metallization, preferably again by a print application process as an aqueous dispersion, so that the first barrier coating assembly 20 with its very thin metallization is arranged between two flexible polymer layers 22 and 18 or 14 and is thereby particularly well protected mechanically against damage.

[0067] The polymer coating 22 in the present first embodiment is preferably formed from a modified polyvinyl alcohol, wherein the formulation of the modified polyvinyl alcohol of the polymer coating 22 is preferably different from that of the first barrier coating assembly 14.

[0068] The modified polyvinyl alcohol of the polymer coating 22 has a higher degree of cross-linking than the PVOH barrier layers 16 and 18 of the first barrier coating assembly 14 in order to create adhesive properties for bonding with the biopolymer coating 24 described below or to improve existing adhesive properties. As the degree of cross-linking of the PVOH of the polymer coating 22 increases, the binding force between the polymer coating 22 and the biopolymer coating 24 made of natural protein applied thereto increases.

[0069] A sealable biopolymer coating 24 is applied to the polymer coating 22, which preferably has a weight per unit area in the range of 0.5 to 5 g / m2 and, in the present example, a specific weight per unit area of 1.5 g / m2, which enables a connection with compatible or identical sealable biopolymer coatings. In this way, hermetically sealed pouch packaging, such as three-or four-side sealed pouches or stand-up pouches, can be formed from cut-to-size pieces of the packaging layer material 10.

[0070] The biopolymer coating 24, which has a preferred weight per unit area in the range of 0.5 to 5 g / m2 and, in the embodiment of FIG. 1, a weight per unit area of 3.5 g / m2, is preferably applied to substantially the entire surface of the polymer coating 22 by a water-based dispersion in a printing application process, in particular in a roller application process. The biopolymer coating is formed from a natural protein, for example casein.

[0071] The polymer coating 22 forms an adhesion promoter layer between the metallization of the second barrier coating assembly 20 and the biopolymer coating 24 and also provides a further oxygen and mineral oil barrier.

[0072] Compared to polyolefin layers of the same thickness, the biopolymer coating 24 is also above average in terms of grease resistance and has above average kink-break resistance, thus also contributing to the protection of the second barrier coating assembly embedded between two flexible polymer layers.

[0073] A print application 26 is applied by printing to the surface 12b of the paper layer 12 facing the subsequent external environment and thus the consumers. The print application 26 comprises a layer of printing ink 28 provided directly on the paper of the paper layer 12, which is preferably designed without print-property improving paper coating, and a transparent layer of protective lacquer 30 made of overprint lacquer covering the layer of printing ink 28. In the embodiment, the layer of protective lacquer 30 and the layer of printing ink 28 are formed from nitrocellulose-based lacquers and inks. The number of different colors in the layer of printing ink 28 depends on the printing process selected for applying the layer of printing ink 28 to the paper.

[0074] The protective lacquer layer 30 also provides a water vapor barrier for the outermost paper layer to reduce moisture permeation through the paper layer. The water vapor permeation is less than 30 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0075] The print application 26, which has a preferred weight per unit area of less than 3 g / m2, allows consumer information to be applied to the subsequent outer side 10b of the packaging layer material 10.

[0076] The packaging layer material 10 can be recycled without any problems. The first barrier coating assembly 14 formed from modified PVOH can be liquefied under the influence of sufficient water so that all coating layers of the packaging layer material 10 located on the surface 12a can be removed from the paper layer 12 and the paper layer 12 can be recycled as printed paper.

[0077] The packaging layer material 10 of the first embodiment also exhibits an excellent barrier against migration of oxygen, moisture, and grease, in particular mineral oil, as well as against the transmission of light.

[0078] The packaging layer material 10 of the example shown has an oxygen permeability over its total thickness of not more than 0.85 cm3 / (m2·d·bar), determined in accordance with DIN 53380-3 at 23° C. and 85% relative humidity, and a water vapor permeability of not more than 0.85 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0079] The water absorption capacity of the packaging layer material 10 of the example shown is less than 0.5%, determined according to method PA154 for COBB value determination with a test duration of 60 seconds, and less than 1%, determined according to method PA154 for COBB value determination with a test duration of 1800 seconds.

[0080] The mineral oil permeation through the packaging layer material 10 of the example shown is less than 1%, determined according to SVI guideline 2015-01 with a test duration of 12.2 days and a test temperature of 60° C.

[0081] The packaging layer material 10 of the example shown has a grease barrier with a KIT value of 12 over its total thickness, determined in accordance with the KIT test known in the technical field.

[0082] The packaging layer material 10 of the example shown has a light transmission of less than 0.1% over its total thickness at a wavelength of 600 nm-190 nm.

[0083] FIG. 2 shows a second embodiment of a packaging layer material according to the invention in roughly schematic cross-section and generally designated by 110.

[0084] Identical and functionally identical components and component sections are designated in the second embodiment of FIG. 2 with the same reference symbols as in the first embodiment of FIG. 1, but increased by the number 100. The second embodiment will be described below only insofar as it differs from the first embodiment described above, to which reference is otherwise made for the description of the second embodiment.

[0085] The difference between the two embodiments essentially concerns the further layers arranged on the surface 20a or 120a of the second barrier coating assembly 20 or 120 pointing towards the subsequent packaging space V.

[0086] In the second embodiment, a polymer coating is also applied to the second barrier coating assembly 120 by printing. Its weight per unit area in the embodiment is also 1.5 g / m2, whereby the weight per unit area of the polymer coating 122 can also be selected in a range from 0.5 to 5 g / m2. However, in the second embodiment, the polymer applied as an aqueous dispersion to the second barrier coating assembly 120 is a polyolefin, in particular polyethylene. A primer may be arranged between the polymer coating 122 made of polyolefins and the second barrier coating assembly 120, which increases the adhesion of the polymer coating 122 to the second barrier coating assembly 120.

[0087] The polyolefin, in particular polyethylene, of the polymer coating 122 has an above-average barrier effect against the migration of moisture / water vapor in relation to its thickness. The polymer coating 122 can therefore not only mechanically protect the metallization of the second barrier coating assembly 120 between two flexible polymer layers, but can also cover any defects in the second barrier coating assembly 120, which also forms a water vapor barrier, and mitigate or eliminate their effect.

[0088] In the second embodiment, the biopolymer coating 124 is considerably thicker than in the first embodiment. This is due, among other things, to the different choice of material. The polymer coating 124 is formed from a biopolymer polyester, in particular PBSA, and has a weight per unit area in the range of 5 to 50 g / m2. In the specific embodiment shown in FIG. 2, the weight per unit area of the polymer coating 124 is 20 g / m2.

[0089] The biopolymer of the biopolymer coating 124 is not applied by printing, but is applied by extrusion, more precisely by coextrusion with a primer layer 123, which is in direct contact with the polymer coating 122. The primer layer 123 coextruded with the polymer coating 124 has a weight per unit area in the range of 0.5 to 5 g / m2 and, in the second embodiment shown, has a specific weight per unit area of 0.9 g / m2. The primer layer 123 increases the adhesion of the biopolymer coating 124 to the polyolefin coating 122.

[0090] Biopolymers generally provide greater flexibility than dispersion coatings and therefore primarily protect the first and second barrier coating assemblies 114 and 120, respectively, from damage due to tearing or puncturing. In addition, the biopolymer coating 124 protects the packaging layer material 110 from kinking.

[0091] The PBSA of the biopolymer coating 124 also allows the biopolymer coating 124 to be sealed to other compatible or identical layers. The higher application weight or thickness of the biopolymer coating 124 compared to that of the biopolymer coating 24 of the first embodiment also allows resealing means, such as so-called “zippers,” to be embedded or anchored in the biopolymer coating 124. This allows mechanically resealable packaging to be formed with the paper-based packaging layer material 110. The resealing means can be produced from a compatible or the same biopolymer as that of the biopolymer coating 124 by extrusion and can be anchored particularly firmly and securely in the biopolymer coating 124 by thermal sealing.

[0092] The barrier values of the second embodiment correspond to the barrier values specified for the first embodiment.

[0093] While considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Examples

first embodiment

[0057]Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, FIG. 1 shows a packaging layer material according to the invention in a roughly schematic cross-sectional view and is generally designated by 10.

[0058]An inner surface 10a of the packaging layer material 10 faces a packaging space V of a package formed from the packaging layer material 10. An opposite outer surface 10b of the packaging layer material 10, on the other hand, faces the external environment U and thus the consumers of the packaging on a packaging formed from the packaging layer material 10.

[0059]The packaging layer material 10 has a paper layer 12 made of uncoated paper with a weight per unit area in the range of 30 to 100 g / m2, preferably 45 to 90 g / m2, as a structure-forming layer. All other layers are supported by the paper layer 12 or applied directly or indirectly to it...

second embodiment

[0083]FIG. 2 shows a packaging layer material according to the invention in roughly schematic cross-section and generally designated by 110.

[0084]Identical and functionally identical components and component sections are designated in the second embodiment of FIG. 2 with the same reference symbols as in the first embodiment of FIG. 1, but increased by the number 100. The second embodiment will be described below only insofar as it differs from the first embodiment described above, to which reference is otherwise made for the description of the second embodiment.

[0085]The difference between the two embodiments essentially concerns the further layers arranged on the surface 20a or 120a of the second barrier coating assembly 20 or 120 pointing towards the subsequent packaging space V.

[0086]In the second embodiment, a polymer coating is also applied to the second barrier coating assembly 120 by printing. Its weight per unit area in the embodiment is also 1.5 g / m2, whereby the weight per...

[0001] This Application claims priority in PCT application PCT / EP2024 / 053186 filed Feb. 8, 2024, which claims priority in German Patent Application DE 10 2023 103 298.4 filed on Feb. 10, 2023, which are incorporated by reference herein.

[0002] The present invention relates to a packaging layer material comprising a base layer of paper, a first barrier coating assembly of a vinyl alcohol polymer and a second barrier coating assembly of a metal or a metal compound which is deposited on a carrier surface in a vapor deposition process.BACKGROUND OF THE INVENTION

[0003] Such a packaging layer material, whether in roll material or sheet material form, is used for the production of packaging. The packaging may be packaging with packaging spaces closed by seals or adhesives, such as pouch packaging, for example three-or four-side sealed pouches or stand-up pouches, or may be packaging formed by wrapping the goods to be packaged.

[0004] Such packaging layer materials are expected to provide a barrier against a variety of external influences on the packaged product. At the same time, they should be environmentally compatible and recyclable. Barriers against oxygen migration are particularly important in order to prevent or at least delay oxidation of the packaged goods, as are barriers against water vapor or moisture in order to prevent unwanted softening or even rotting of the packaged product.

[0005] In the case of paper-based packaging layer materials, a barrier protection of the paper layer against migration of moisture, oil, and / or fat from the packaged product into the paper layer may also be necessary. Paper is often absorbent due to its porosity and can permanently store moisture, oil, and / or grease in its structure, which, however, usually adversely affects the structure in terms of its strength and / or appearance.

[0006] Recyclability and environmental compatibility are provided by the base layer made of paper. However, in the prior art, barriers are often achieved by metal foils, the production of which, however, requires a high amount of energy and resources. Alternatively, barriers can be achieved by polymer coatings made of polyvinylidene chloride, which, however, considerably impairs the recyclability of the layer composite produced in this way.SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a paper-based packaging layer material with a high barrier effect that is as environmentally compatible and recyclable as possible.

[0008] The present invention solves this problem with a packaging layer material mentioned at the beginning, whose first barrier coating assembly has more than one layer of the vinyl alcohol polymer, wherein the layers of the first barrier coating assembly are arranged directly one after the other.

[0009] The use of paper as the material for the base layer ensures that the structure-forming portion of the packaging layer material is recyclable. By forming the first barrier coating assembly from a vinyl alcohol polymer, the first barrier coating assembly can be formed as a water-soluble separating layer which, upon contact with water, dissolves and thereby separates the paper base layer from further layers of the packaging layer material.

[0010] By stacking at least two layers of the vinyl alcohol polymer, one layer of the first barrier coating assembly can cover any defects in another layer of the first barrier coating assembly. In this way, any cracks, tears, and holes that occur in one layer can be covered by material from another layer, and any impairment of the barrier against oxygen migration provided by the first barrier coating assembly can be reduced or even completely eliminated.

[0011] The paper layer preferably has a weight per unit area in the range of 30 to 100 g / m2, particularly preferably in the range of 45 to 90 g / m2. While the paper base layer can in principle be formed from two or more interconnected partial paper layers, the paper base layer is preferably formed from a single paper layer.

[0012] The first barrier coating assembly preferably has a weight per unit area in the range of 1 to 10 g / m2.

[0013] While a vinyl alcohol polymer is susceptible to attack by water, but provides a very good barrier against oxygen migration, the second barrier coating assembly, which is formed with a very low thickness in the range of 10 to 80 nm as a coating deposited from a vapor phase, forms an excellent barrier against migration of water vapor or moisture through the packaging layer material. Depending on the thickness and material of the deposited coating of metal or a metal compound, the second barrier coating assembly can also form a light barrier and thus protect light-sensitive packaged products.

[0014] In principle, the first barrier coating assembly can have a plurality of layers of vinyl alcohol polymer, for example two or three or four layers. However, tests have shown that even a stacked arrangement of exactly two layers of vinyl alcohol polymer provides an excellent and, above all, uninterrupted barrier against oxygen migration through the packaging layer material over its entire surface area. In order to avoid unnecessary effort that does not contribute to any significant improvement in the oxygen barrier effect, the first barrier coating assembly preferably comprises exactly two layers of vinyl alcohol polymer.

[0015] Each layer of the first barrier coating assembly preferably has a weight per unit area in the range of 0.5 to 5g / m2. This does not mean that all layers of the first barrier coating assembly have a uniform weight per unit area, although this is preferred for manufacturing reasons.

[0016] Preferably, the packaging layer material has an oxygen permeability over its total thickness of not more than 1.0, preferably not more than 0.85 cm3 / (m2·d·bar), determined in accordance with DIN 53380-3 at 23° C. and 85% relative humidity, and a water vapor permeability of not more than 1.0, preferably not more than 0.85 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0017] Although the individual layers of the first barrier coating assembly may contain different vinyl alcohol polymers, the use of vinyl alcohol polymers based on at least the same monomer or the same monomers is preferred. It is particularly preferred that all layers of the first barrier coating assembly are formed from the same vinyl alcohol polymer. This ensures particularly good adhesion of the individual layers of the first barrier coating assembly to one another.

[0018] The vinyl alcohol polymer is preferably a modified vinyl alcohol polymer whose properties in terms of moisture resistance and elasticity are optimized by the processing method using temperature and humidity control during drying, which is particularly good at compensating for defects in one layer, known in the technical field as “pinholes,” by means of an overlying layer.

[0019] The vinyl alcohol polymer layers are preferably applied by printing, for example by roller coating. This allows vinyl alcohol polymer layers applied one after the other by printing to be subject to different influences. Consequently, each of the layers can and will usually form cracks, tears and, in particular, the above-mentioned pinholes at different locations, so that, as already explained above, defects in one layer are covered by the other layer and vice versa.

[0020] It is particularly preferred that the first barrier coating assembly is applied directly to a surface of the paper base layer.

[0021] According to a preferred refinement of the present invention, the vinyl alcohol polymer may comprise or be polyvinyl alcohol (PVOH) and / or butenediol-vinyl alcohol copolymer (BVOH). Polyvinyl alcohol, particularly in the modified form mentioned above, can provide particularly good defect compensation for layers arranged one above the other. In addition to the barrier against oxygen migration, polyvinyl alcohol also provides a very good barrier against the migration of mineral oil through the packaging layer material.

[0022] Butenediol-vinyl alcohol copolymer has the advantage of excellent biodegradability.

[0023] In principle, it is conceivable to deposit the second barrier coating assembly directly onto a surface of the paper base layer. However, this usually requires pretreatment of the carrier surface formed by the paper base layer in order to close pores in the typically porous paper. Otherwise, due to the low thickness of the deposited second barrier coating assembly, fibers of the paper base layer could be coated with the metal or metal compound, but without closing the or all pores in the material, so that the barrier effect desired by the second barrier coating assembly could be lost. To avoid the expense of pretreating the paper, the first barrier coating assembly is preferably arranged between the paper base layer and the second barrier coating assembly. In particular, one surface of the first barrier coating assembly forms the carrier surface of the second barrier coating assembly. If necessary, a primer layer may be provided between the first and second barrier coating assemblies. However, it is preferable to deposit the second barrier coating assembly directly onto the first barrier coating assembly.

[0024] A further advantage of arranging the first barrier coating assembly between the paper base layer and the second barrier coating assembly lies in the protection of the first barrier coating assembly against moisture attack by the second barrier coating assembly, which shields the first barrier coating assembly.

[0025] The second barrier coating assembly comprises a deposited layer of metal or of a metal oxide as the metal compound mentioned above. The metal can be any metal, such as gold, silver, platinum, copper, or aluminum. A deposited metal layer is preferably an aluminum layer or a layer of an aluminum alloy. Such a metal layer can be provided to be light-tight.

[0026] If a metal oxide is desired as the deposited second barrier coating assembly, which can often be deposited in an even thinner layer than metal, the material of the second barrier coating assembly comprises or is silicon oxide or aluminum oxide.

[0027] In a preferred refinement of the present invention, a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer in order to protect the deposited, i.e. usually vapor-deposited, second barrier coating assembly. It has been found that when the second barrier coating assembly deposited from the vapor phase is arranged between two flexible layers, in particular polymer layers, it is particularly mechanically resistant and can be bent or even folded without any risk of cracks or tears in the second barrier coating assembly.

[0028] With a suitable choice of material, the polymer coating can be applied directly to a surface of the second barrier coating assembly. If necessary, a primer layer can be applied to the second barrier coating assembly to increase the adhesion of the polymer coating to the second barrier coating assembly.

[0029] The polymer coating may comprise or be a vinyl alcohol polymer if an even higher barrier effect against oxygen migration through the packaging layer material is desired. When PVOH is used as the vinyl alcohol polymer of the polymer coating, the barrier effect against migration of mineral oil through the packaging layer material can also be increased. Any of the vinyl alcohol polymers mentioned above are particularly suitable as the vinyl alcohol polymer. The vinyl alcohol polymer is particularly preferred as a modified vinyl alcohol polymer, particularly preferred as a modified PVOH, although a formulation of the modified PVOH of the polymer coating that differs from the modified PVOH of the first barrier coating assembly is preferred. Reference is made to the above description for the modification of the PVOH.

[0030] Preferably, the PVOH of the polymer coating has a higher degree of crosslinking than PVOH, preferably than the entire PVOH of the first barrier coating arrangement, in order to improve the adhesion of a further polymer, in particular the biopolymer coating explained below, thereto. Preferably, the PVOH of the first barrier coating assembly has a higher degree of crystallization than the PVOH of the polymer coating in order to improve the moisture stability of the first barrier coating assembly. The adjustment of a relative or absolute degree of crosslinking and / or a relative or absolute degree of crystallization is also a modification of the PVOH within the meaning of the present application.

[0031] Alternatively, the polymer coating may comprise or be a polyolefin. This allows the water vapor barrier provided by the second barrier coating assembly to be further improved in its effect, especially when polyethylene is used as the polyolefin of the polymer coating. The polymer coating made of polyolefins, in particular polyethylene, can thus cover any cracks, gaps or holes present in the second barrier coating assembly and thus close barrier gaps or at least reduce their effect.

[0032] The polymer coating is preferably applied as a water-based dispersion in a print application, for example by roller coating.

[0033] The polymer coating has a preferred weight per unit area in the range of 0.5 to 5 g / m2, wherein an application in the range of 1 to 2.5 g / m2 is preferred and a weight per unit area of 1.5 g / m2 is particularly preferred.

[0034] All weights per unit area mentioned in the present application refer to the respective layer in the dry state.

[0035] A biopolymer coating may also be arranged on the side of the second barrier coating assembly facing away from the paper base layer. For the purposes of this application, a biopolymer is any biodegradable polymer that complies with European standard EN 13432. A biodegradable polymer is generally a polymer that can be decomposed by microorganisms such as fungi or bacteria, by means of enzymes under certain conditions, in less than one year. The decomposition takes place mainly through oxidation and hydrolysis processes to the decomposition products water, carbon dioxide or methane and biomass.

[0036] The above-mentioned polymer coating is preferably arranged between the second barrier coating assembly and the biopolymer coating. Then, if a vinyl alcohol polymer, in particular PVOH, is selected as one or as the material of the polymer coating, the vinyl alcohol polymer can additionally act as a tie layer to increase the adhesion of the biopolymer coating to the layer composite already described above.

[0037] According to a particularly preferred refinement of the present invention, the biopolymer coating may be based on a natural protein or may be constructed from a protein polymer based on natural protein, for example comprising or consisting of casein, or may comprise a biodegradable polyester or be formed from such a polyester. A particularly preferred polyester made from biopolymer is polybutylene succinate adipate, or PBSA for short.

[0038] If a polyolefin is chosen as the polymer coating, a primer is preferably applied, preferably by extrusion, to increase the adhesion of the biopolymer coating to the polymer coating. The primer is particularly preferred to be coextruded with the biopolymer.

[0039] The biopolymer coating preferably has a weight per unit area in the range of 0.5 to 50 g / m2. The weights per unit area used for the different biopolymers are preferably different. A biopolymer based on natural protein preferably has a weight per unit area in the range of 0.5 to 5 g / m2, a particularly preferred weight per unit area being in the range of 2.8 to 4.2 g / m2, and a particularly preferred biopolymer coating made from a protein polymer based on a natural protein having a weight per unit area of 3.5 g / m2. The biopolymer based on natural protein is preferably applied in aqueous dispersion by printing, for example by roller coating, preferably directly onto the polymer coating lying immediately underneath, in particular made of modified PVOH.

[0040] A polyester as the biopolymer of the biopolymer coating, in particular the above-mentioned PBSA, has a preferred weight per unit area of 5 to 50 g / m2, with a more preferred weight per unit area range of 10 to 30 g / m2, and a biopolymer coating made of PBSA in a preferred embodiment has a weight per unit area of 20 g / m2.

[0041] The use of biopolymers, in particular polyester, protects the packaging formed from the packaging layer material against breaking by kinking and also protects the underlying barrier coating assemblies against mechanical damage caused by tearing and puncturing.

[0042] The biopolymer coating, when applied in sufficient thickness, can also be used to anchor closure means, such as so-called “zippers,” in the packaging layer material on the side of the polymer coating.

[0043] If a primer arrangement is necessary to increase the adhesion of the biopolymer coating to the polymer coating, the primer layer provided then has a preferred weight per unit area in the range of 0.5 to 5 g / m2, whereby a weight per unit area in the range of 0.7 to 1.7 g / m2 is particularly preferred. In a preferred embodiment, a primer layer arranged between the polymer coating and the biopolymer coating has a weight per unit area of 0.9 g / m2.

[0044] For easy formation of packaging, the biopolymer coating is preferably sealable or has a sealable exposed surface.

[0045] Biopolymers also provide a further barrier against migration of mineral oil, grease, and moisture through the packaging layer material.

[0046] To provide consumer information, the packaging material preferably has a print application. The print application is preferably applied directly to the paper base layer. Therefore, the print application on the one hand and the first and second barrier coating assemblies, as well as any further polymer layers, preferably all polymer layers, are preferably located on different sides of the paper base layer.

[0047] The colors of the print application are preferably solvent-based colors. However, water-based colors may also be used. Although water in this sense is also an abstract solvent, the term “solvent-based” in the present application refers to the use of solvents other than water.

[0048] To prevent printing inks from rubbing off when touched, the print application may preferably comprise an overprint varnish over a printing ink application. The overprint varnish may be a solvent-based overprint varnish based on nitrocellulose or may be a polyolefin, which is preferably applied as an aqueous dispersion.

[0049] The entire print application, including an overprint varnish, preferably has a weight per unit area of less than 3.2 g / m2 when dry.

[0050] The paper base layer is preferably free of a print-property improving paper coating. This prevents a print-property improving paper coating, which is not present anyway, from breaking and thus inducing the breakage of adjacent coatings. The paper base layer is preferably completely uncoated.

[0051] Preferred embodiments of the packaging layer material presented here only have the layers mentioned above.

[0052] These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section.BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which forms a part hereof and wherein:

[0054] FIG. 1 a roughly schematic cross-sectional view through a first embodiment of a packaging layer material according to the invention, and

[0055] FIG. 2 a roughly schematic cross-sectional view through a second embodiment of a packaging layer material according to the invention.

[0056] The figures are not to scale.DESCRIPTION OF PREFERRED EMBODIMENTS

[0057] Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, FIG. 1 shows a first embodiment of a packaging layer material according to the invention in a roughly schematic cross-sectional view and is generally designated by 10.

[0058] An inner surface 10a of the packaging layer material 10 faces a packaging space V of a package formed from the packaging layer material 10. An opposite outer surface 10b of the packaging layer material 10, on the other hand, faces the external environment U and thus the consumers of the packaging on a packaging formed from the packaging layer material 10.

[0059] The packaging layer material 10 has a paper layer 12 made of uncoated paper with a weight per unit area in the range of 30 to 100 g / m2, preferably 45 to 90 g / m2, as a structure-forming layer. All other layers are supported by the paper layer 12 or applied directly or indirectly to it. The paper of the paper layer 12 is recyclable and is preferably also approved for packaging foodstuffs.

[0060] A first barrier coating assembly 14 is applied, preferably by a printing process, for example in a roller coating process, as an aqueous dispersion to the surface 12a of the paper layer 12 facing the subsequent packaging space V. The barrier coating assembly 14 is applied over the entire surface 12a of the paper layer 12, disregarding edge areas of the packaging layer material 10 which form trimmings in further processing.

[0061] In the present embodiment, the first barrier coating assembly 14 is formed from two layers 16 and 18 of modified polyvinyl alcohol as described above, which are applied one after the other. The layers 16 and 18 each have a weight per unit area in the range of 0.5 to 5 g / m2 and, in the preferred embodiment, each have a weight per unit area of 1.5 g / m2. In the present embodiment, the two layers 16 and 18 of the first barrier coating assembly 14 are identical in terms of material composition and weight per unit area, but this is not necessary.

[0062] The polyvinyl alcohol of the first barrier coating assembly provides a barrier against the migration of oxygen and mineral oil through the packaging layer material 10. Due to the advantageously high degree of crystallinity of the polyvinyl alcohol, the first barrier coating assembly 14 is more stable against moisture attack than conventional polyvinyl alcohol with a lower degree of crystallinity, despite the fundamental moisture sensitivity of polyvinyl alcohol.

[0063] The layers 16 and 18 are preferably applied one after the other so that, when the first layer 16 dries, any defects forming in it, such as cracks, tears, and holes, which could reduce the barrier properties of layer 16, can be covered by material from layer 18 applied immediately onto layer 16. Similarly, cracks, tears, and holes in layer 18 are bridged and covered by the underlying layer 16. It is very unlikely that defects will form in exactly the same place in two successive PVOH-containing barrier layers 16 and 18 of the first barrier coating assembly 14.

[0064] On the free surface 18a of layer 18, which points away from the paper layer 12 and toward the subsequent packaging space V and which is also the free surface 14a of the first barrier coating assembly 14, as a carrier surface an aluminum alloy is deposited as a metallization in a physical or chemical vapor deposition process, preferably in a physical vapor deposition process. The metallization forms a second barrier coating assembly 20, which is 10 to 80 nm thick and, in the present example, provides a barrier against light and against water vapor or moisture.

[0065] The first barrier coating assembly 14 made of modified PVOH forms an advantageously smooth surface 14a, which allows for continuous metallization that is as free of defects as possible.

[0066] A polymer coating 22 is applied to the metallization, preferably again by a print application process as an aqueous dispersion, so that the first barrier coating assembly 20 with its very thin metallization is arranged between two flexible polymer layers 22 and 18 or 14 and is thereby particularly well protected mechanically against damage.

[0067] The polymer coating 22 in the present first embodiment is preferably formed from a modified polyvinyl alcohol, wherein the formulation of the modified polyvinyl alcohol of the polymer coating 22 is preferably different from that of the first barrier coating assembly 14.

[0068] The modified polyvinyl alcohol of the polymer coating 22 has a higher degree of cross-linking than the PVOH barrier layers 16 and 18 of the first barrier coating assembly 14 in order to create adhesive properties for bonding with the biopolymer coating 24 described below or to improve existing adhesive properties. As the degree of cross-linking of the PVOH of the polymer coating 22 increases, the binding force between the polymer coating 22 and the biopolymer coating 24 made of natural protein applied thereto increases.

[0069] A sealable biopolymer coating 24 is applied to the polymer coating 22, which preferably has a weight per unit area in the range of 0.5 to 5 g / m2 and, in the present example, a specific weight per unit area of 1.5 g / m2, which enables a connection with compatible or identical sealable biopolymer coatings. In this way, hermetically sealed pouch packaging, such as three-or four-side sealed pouches or stand-up pouches, can be formed from cut-to-size pieces of the packaging layer material 10.

[0070] The biopolymer coating 24, which has a preferred weight per unit area in the range of 0.5 to 5 g / m2 and, in the embodiment of FIG. 1, a weight per unit area of 3.5 g / m2, is preferably applied to substantially the entire surface of the polymer coating 22 by a water-based dispersion in a printing application process, in particular in a roller application process. The biopolymer coating is formed from a natural protein, for example casein.

[0071] The polymer coating 22 forms an adhesion promoter layer between the metallization of the second barrier coating assembly 20 and the biopolymer coating 24 and also provides a further oxygen and mineral oil barrier.

[0072] Compared to polyolefin layers of the same thickness, the biopolymer coating 24 is also above average in terms of grease resistance and has above average kink-break resistance, thus also contributing to the protection of the second barrier coating assembly embedded between two flexible polymer layers.

[0073] A print application 26 is applied by printing to the surface 12b of the paper layer 12 facing the subsequent external environment and thus the consumers. The print application 26 comprises a layer of printing ink 28 provided directly on the paper of the paper layer 12, which is preferably designed without print-property improving paper coating, and a transparent layer of protective lacquer 30 made of overprint lacquer covering the layer of printing ink 28. In the embodiment, the layer of protective lacquer 30 and the layer of printing ink 28 are formed from nitrocellulose-based lacquers and inks. The number of different colors in the layer of printing ink 28 depends on the printing process selected for applying the layer of printing ink 28 to the paper.

[0074] The protective lacquer layer 30 also provides a water vapor barrier for the outermost paper layer to reduce moisture permeation through the paper layer. The water vapor permeation is less than 30 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0075] The print application 26, which has a preferred weight per unit area of less than 3 g / m2, allows consumer information to be applied to the subsequent outer side 10b of the packaging layer material 10.

[0076] The packaging layer material 10 can be recycled without any problems. The first barrier coating assembly 14 formed from modified PVOH can be liquefied under the influence of sufficient water so that all coating layers of the packaging layer material 10 located on the surface 12a can be removed from the paper layer 12 and the paper layer 12 can be recycled as printed paper.

[0077] The packaging layer material 10 of the first embodiment also exhibits an excellent barrier against migration of oxygen, moisture, and grease, in particular mineral oil, as well as against the transmission of light.

[0078] The packaging layer material 10 of the example shown has an oxygen permeability over its total thickness of not more than 0.85 cm3 / (m2·d·bar), determined in accordance with DIN 53380-3 at 23° C. and 85% relative humidity, and a water vapor permeability of not more than 0.85 g / (m2·d), determined in accordance with ISO 15106-2 at 23° C. and 85% relative humidity.

[0079] The water absorption capacity of the packaging layer material 10 of the example shown is less than 0.5%, determined according to method PA154 for COBB value determination with a test duration of 60 seconds, and less than 1%, determined according to method PA154 for COBB value determination with a test duration of 1800 seconds.

[0080] The mineral oil permeation through the packaging layer material 10 of the example shown is less than 1%, determined according to SVI guideline 2015-01 with a test duration of 12.2 days and a test temperature of 60° C.

[0081] The packaging layer material 10 of the example shown has a grease barrier with a KIT value of 12 over its total thickness, determined in accordance with the KIT test known in the technical field.

[0082] The packaging layer material 10 of the example shown has a light transmission of less than 0.1% over its total thickness at a wavelength of 600 nm-190 nm.

[0083] FIG. 2 shows a second embodiment of a packaging layer material according to the invention in roughly schematic cross-section and generally designated by 110.

[0084] Identical and functionally identical components and component sections are designated in the second embodiment of FIG. 2 with the same reference symbols as in the first embodiment of FIG. 1, but increased by the number 100. The second embodiment will be described below only insofar as it differs from the first embodiment described above, to which reference is otherwise made for the description of the second embodiment.

[0085] The difference between the two embodiments essentially concerns the further layers arranged on the surface 20a or 120a of the second barrier coating assembly 20 or 120 pointing towards the subsequent packaging space V.

[0086] In the second embodiment, a polymer coating is also applied to the second barrier coating assembly 120 by printing. Its weight per unit area in the embodiment is also 1.5 g / m2, whereby the weight per unit area of the polymer coating 122 can also be selected in a range from 0.5 to 5 g / m2. However, in the second embodiment, the polymer applied as an aqueous dispersion to the second barrier coating assembly 120 is a polyolefin, in particular polyethylene. A primer may be arranged between the polymer coating 122 made of polyolefins and the second barrier coating assembly 120, which increases the adhesion of the polymer coating 122 to the second barrier coating assembly 120.

[0087] The polyolefin, in particular polyethylene, of the polymer coating 122 has an above-average barrier effect against the migration of moisture / water vapor in relation to its thickness. The polymer coating 122 can therefore not only mechanically protect the metallization of the second barrier coating assembly 120 between two flexible polymer layers, but can also cover any defects in the second barrier coating assembly 120, which also forms a water vapor barrier, and mitigate or eliminate their effect.

[0088] In the second embodiment, the biopolymer coating 124 is considerably thicker than in the first embodiment. This is due, among other things, to the different choice of material. The polymer coating 124 is formed from a biopolymer polyester, in particular PBSA, and has a weight per unit area in the range of 5 to 50 g / m2. In the specific embodiment shown in FIG. 2, the weight per unit area of the polymer coating 124 is 20 g / m2.

[0089] The biopolymer of the biopolymer coating 124 is not applied by printing, but is applied by extrusion, more precisely by coextrusion with a primer layer 123, which is in direct contact with the polymer coating 122. The primer layer 123 coextruded with the polymer coating 124 has a weight per unit area in the range of 0.5 to 5 g / m2 and, in the second embodiment shown, has a specific weight per unit area of 0.9 g / m2. The primer layer 123 increases the adhesion of the biopolymer coating 124 to the polyolefin coating 122.

[0090] Biopolymers generally provide greater flexibility than dispersion coatings and therefore primarily protect the first and second barrier coating assemblies 114 and 120, respectively, from damage due to tearing or puncturing. In addition, the biopolymer coating 124 protects the packaging layer material 110 from kinking.

[0091] The PBSA of the biopolymer coating 124 also allows the biopolymer coating 124 to be sealed to other compatible or identical layers. The higher application weight or thickness of the biopolymer coating 124 compared to that of the biopolymer coating 24 of the first embodiment also allows resealing means, such as so-called “zippers,” to be embedded or anchored in the biopolymer coating 124. This allows mechanically resealable packaging to be formed with the paper-based packaging layer material 110. The resealing means can be produced from a compatible or the same biopolymer as that of the biopolymer coating 124 by extrusion and can be anchored particularly firmly and securely in the biopolymer coating 124 by thermal sealing.

[0092] The barrier values of the second embodiment correspond to the barrier values specified for the first embodiment.

[0093] While considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Examples

first embodiment

[0057]Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, FIG. 1 shows a packaging layer material according to the invention in a roughly schematic cross-sectional view and is generally designated by 10.

[0058]An inner surface 10a of the packaging layer material 10 faces a packaging space V of a package formed from the packaging layer material 10. An opposite outer surface 10b of the packaging layer material 10, on the other hand, faces the external environment U and thus the consumers of the packaging on a packaging formed from the packaging layer material 10.

[0059]The packaging layer material 10 has a paper layer 12 made of uncoated paper with a weight per unit area in the range of 30 to 100 g / m2, preferably 45 to 90 g / m2, as a structure-forming layer. All other layers are supported by the paper layer 12 or applied directly or indirectly to it...

second embodiment

[0083]FIG. 2 shows a packaging layer material according to the invention in roughly schematic cross-section and generally designated by 110.

[0084]Identical and functionally identical components and component sections are designated in the second embodiment of FIG. 2 with the same reference symbols as in the first embodiment of FIG. 1, but increased by the number 100. The second embodiment will be described below only insofar as it differs from the first embodiment described above, to which reference is otherwise made for the description of the second embodiment.

[0085]The difference between the two embodiments essentially concerns the further layers arranged on the surface 20a or 120a of the second barrier coating assembly 20 or 120 pointing towards the subsequent packaging space V.

[0086]In the second embodiment, a polymer coating is also applied to the second barrier coating assembly 120 by printing. Its weight per unit area in the embodiment is also 1.5 g / m2, whereby the weight per...

Claims

1-17. (canceled)18. A packaging layer material comprising a base layer made of paper, a first barrier coating assembly made of a vinyl alcohol polymer, and a second barrier coating assembly of a metal or a metal compound which is deposited on a carrier surface in a vapor deposition process,wherein the first barrier coating assembly comprises more than one layer of the vinyl alcohol polymer, wherein the layers of the first barrier coating assembly are arranged directly one after the other.

19. The packaging layer material according to claim 18, wherein the first barrier coating assembly comprises exactly two layers.

20. The packaging layer material according to claim 18, wherein the vinyl alcohol polymer is a modified vinyl alcohol polymer.

21. The packaging layer material according to claim 18, wherein vinyl alcohol polymer comprises or is polyvinyl alcohol and / or butenediol-vinyl alcohol copolymer.

22. The packaging layer material according to claim 18, wherein the first barrier coating assembly is arranged between the paper base layer and the second barrier coating assembly.

23. The packaging layer material according to claim 18, wherein the second barrier coating assembly comprises or is a deposited layer of metal or of a metal oxide.

24. The packaging layer material according to claim 18, wherein a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer.

25. The packaging layer material according to claim 24, wherein the polymer coating comprises or is a vinyl alcohol polymer or a polyolefin.

26. The packaging layer material according to claim 24, wherein the polymer coating is applied as a water-based dispersion in a print application.

27. The packaging layer material according to claim 18, wherein a biopolymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer.

28. The packaging layer material according to claim 27, wherein a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer, the polymer coating being arranged between the second barrier coating assembly and the biopolymer coating.

29. The packaging layer material according to claim 27, wherein the biopolymer coating is based on a natural protein or comprises a biodegradable polyester or is formed from such.

30. The packaging layer material according to claim 27, wherein the biopolymer coating is sealable.

31. The packaging layer material according to claim 18, wherein the packaging layer material has a print application.

32. The packaging layer material according to claim 18, wherein the paper base layer is free of a print-property improving paper coating.

33. The packaging layer material according to claim 21, wherein a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer, the polymer coating comprising or is a vinyl alcohol polymer or a polyolefin, the first barrier coating assembly and the first polymer coating each comprise PVOH as vinyl alcohol polymer, wherein the PVOH of the polymer coating has a higher degree of crosslinking than PVOH of the first barrier coating assembly.

34. The packaging layer material according to claim 21, wherein a polymer coating is arranged on the side of the second barrier coating assembly facing away from the paper base layer, the polymer coating comprising or is a vinyl alcohol polymer or a polyolefin, the first barrier coating assembly and the first polymer coating each comprise PVOH as the vinyl alcohol polymer, wherein the PVOH of the polymer coating of the first barrier coating assembly has a higher degree of crystallization than the PVOH of the polymer coating.

Images